This paper reviews the main factors influencing the synthesis of vitamin D, with particular focus on ultraviolet radiation exposure. On the global level, the main source of vitamin D is the sun. The effect of solar radiation on vitamin D synthesis depends to some extent on the initial vitamin D levels. At moderate to high latitudes, diet becomes an increasingly important source of vitamin D due...

Most of the positive effects of solar radiation are mediated via ultraviolet-B (UVB) induced production of vitamin D in skin. However, several other pathways may exist for the action of ultraviolet (UV) radiation on humans as focused on in this review. One is induction of cosmetic tanning (immediate pigment darkening, persistent pigment darkening and delayed tanning). UVB-induced, delayed tanni...

The synthesis of vitamin D in skin is a two-stage process that begins with the production of previtamin D after irradiation of 7-dehydrocholesterol by ultraviolet (UV) radiation. A number of personal and environmental factors control the probability of a suitable UV photon reaching a molecule of 7-dehydrocholesterol in the skin. These are astronomical factors that govern the solar zenith angle ...

Introduction: Normal exposure to sunlight results in the production of vitamin D in human body, which happens because of the interaction between ultraviolet radiation and cholesterol in skin. Exposure to sunlight is responsible for 90 percent of vitamin D needed for the body. Studies show that Iran is a country with high percentage of lack of vitamin D (83 percent). Based on pr...

Introduction: Ultraviolet index (UVI) is a dimensionless scale, which describes the maximum intensity and biologic effects of UV during a specific time, on surface of the earth. The UVI is  an  international  standard measurement of  the  strength  of sunburn  producing ultraviolet radiation at a particular place and time. This index is an easy and understandable concept for pr...

Introduction: Solar radiation has a major role in design, utilization, development, and planning of solar energy. The most important source of natural ultraviolet radiation is the sun, which has an important role in many biologic processes. Some of these processes are useful, like the production of vitamin D in the body, or curing rickets, and some of them are not, such as ski...

introduction: ultraviolet (uv) radiation affects human organs such as skin, eyes and immune system, as well as animals and plants. the main natural source of uv radiation is the sun. to study the effects of solar uv radiation there is a need to quantify variations of solar energy received on the earth surface at different intervals. materials and methods: to measure uv radiation a broadband fib...

Introduction: Solar energy is one of the free sources, clean and environmentally friendly energy. Sun is the most important source of natural ultraviolet radiation that has a major role in the life of living beings. Industrial and medical applications of ultraviolet radiation have been clearly proven, like the production of vitamin D or treatment of many diseases, and also har...

Solar ultraviolet (UV) radiation is one of the most important factors in the development of skin cancer in human, solar erythema and skin aging. Nevertheless, numerous studies have shown the benefits of UV solar radiation in moderate doses, such as the reduction of blood pressure and mental health, treatment of various diseases, and the synthesis of vitamin D in the skin. This paper analyses da...

There is an ongoing debate how to balance between beneficial and adverse effects of UV-exposure. On the one hand, solar UV-radiation represents the most important environmental risk factor for the development of non-melanoma skin cancer. Therefore, sun protection is a key principle to prevent these malignancies, especially in risk groups. On the other hand, artificial or solar UV-radiation is r...